Roofing underlayment

ABSTRACT

A roofing underlayment comprising a carrier substrate included a felt mixture and a binder mixture, and a volume of asphalt flux saturating the carrier substrate. The felt mixture may comprise between about seventy-five percent and about ninety-five percent by weight corrugated paper/cardboard fibers and between about five percent and about twenty-five percent by weight fiberglass fibers. The volume of asphalt flux may comprise between about twenty-five and fifty percent of a total weight of the roofing shingle underlayment and may saturate the carrier substrate at a saturation percentage between about thirty and about one hundred percent. The binder mixture may include a mixture of alum and rosin having a mixture ratio by weight of alum to rosin in a range between one to one (1:1) and four to one (4:1).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application No. 61/899,054 filed Nov. 1, 2013, the entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

This present invention relates to a roofing underlayment having a substrate which allows the underlayment to maintain water resistant and performance characteristics while requiring less asphalt to be absorbed than a traditional underlayment.

BACKGROUND OF THE INVENTION

The costs of asphalt and other petroleum based products have steadily risen, thereby, influencing the market prices for all products which contain asphalt and/or other petroleum based products. The increase in the cost of asphalt flux that is used for producing conventional asphalt-saturated roofing felt has resulted in manufacturers attempting to optimize the amount of asphalt that is used in conventional roofing felt.

Traditional saturated felt roofing underlayment is typically offered in No. 15 and No. 30 grades. Current manufacturers have economized the construction of traditional No. 15 grade felt underlayment by using as little asphalt as possible. However, the optimization of asphalt in conventional roofing felt must also factor in maintaining the user expected and industry-standard performance characteristics. Accordingly, conventional asphalt-saturated roofing felt requires at least a seventy percent to eighty percent (70%-80%) minimum saturation percentage to maintain the industry-standard minimum performance characteristics. Synthetic woven fabrics and mat-type products have been introduced in an attempt to entirely replace asphalt-saturated roofing felt for use in both residential and commercial construction. However, these specialty mats still are more expensive to produce than the conventional asphalt-saturated roofing felt having a seventy percent to eighty percent (70%-80%) minimum saturation. While asphalt-saturated roofing felt remains the lowest cost material to use as a roof underlayment, this trend may not continue due to the increase in the price of crude oil and derived petroleum products.

Thus, there is a need in the art for a roofing underlayment that includes an asphalt-saturated substrate, but requires less asphalt than conventional roofing felt to increase material efficiency, and also retains the industry-standard minimum performance characteristics for roofing underlayment.

SUMMARY OF THE INVENTION

The present invention relates to a roofing underlayment material which may also be used as an underlayment for siding, floors, or for any other water resistant applications similar to conventional asphalt-saturated roofing felt. The substrate of the present invention improves on existing roofing felt through a new composition of the substrate. The substrate composition allows the substrate to absorb less asphalt than conventional roofing felt, but while still maintaining the industry-standard minimum waterproofing and performance characteristics. As such, the present roofing underlayment construction may provide a substantial cost savings while providing identical, if not improved, waterproofing and performance characteristics.

The present roofing underlayment comprises a carrier substrate comprising a felt mixture and a binder mixture, and a volume of asphalt flux saturating said carrier substrate. One embodiment of the present roofing underlayment includes the felt mixture comprising between seventy-five and ninety-five percent (75-95%) by weight corrugated paper/cardboard fibers and between five and twenty-five percent (5-25%) by weight fiberglass fibers. In addition, an embodiment of the present roofing underlayment may include the felt mixture including wood fibers in a percentage between zero and twenty percent (0-20%).

Another embodiment of the present roofing underlayment includes the binder mixture comprising a mixture of alum and rosin having a mixture ratio by weight of alum to rosin in a range between one to one (1:1) and four to one (4:1) and may further include the felt mixture comprising between seventy-five and ninety-five percent (75%-95%) by weight corrugated paper fibers and between five and twenty-five percent (5%-25%) by weight fiberglass fibers. This embodiment may include the volume of asphalt flux comprising between twenty-five and fifty percent (25-50%) of a total weight of said roofing shingle underlayment, wherein the asphalt flux saturates said carrier substrate at a saturation percentage between thirty and one hundred percent (30-100%), with a preferred embodiment including the volume of asphalt flux saturates said carrier substrate at a saturation percentage between forty and sixty percent (40-60%).

The carrier substrate may comprise between fifty and seventy-five percent (50-75%) of the total weight of said roofing underlayment in one or more embodiments of the present roofing underlayment.

Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings form a part of the specification and are to be read in conjunction therewith, in which like reference numerals are employed to indicate like or similar parts in the various views.

FIG. 1 is a table presenting the listing of components and relative percentages for one embodiment of a roofing underlayment in accordance with the teachings of the present invention;

FIG. 2 is a table presenting a listing of components and relative percentages for another embodiment of a roofing underlayment in accordance with the teachings of the present invention; and

FIG. 3 is a table presenting felt gauge, saturation percentages, and components for two embodiments of a roofing underlayment in accordance with the teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description of the present invention references the accompanying drawing figures that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the present invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the spirit and scope of the present invention. The present invention is defined by the appended claims and, therefore, the description is not to be taken in a limiting sense and shall not limit the scope of equivalents to which such claims are entitled.

The roofing underlayment of the present invention includes an asphalt-saturated carrier substrate. Embodiments of the present roofing underlayment may be manufactured into any number of versions; however, two preferable versions have the functional equivalence of both conventional No. 15 and No. 30 grade asphalt-saturated roofing felt. Thus, these two embodiments may be put into the market as meeting equivalent building specifications.

The present carrier substrate may comprise a combination of a felt mixture and a rosin/alum mixture. The felt mixture may comprise around eighty-five to ninety-eight percent (85-98%) of the total carrier substrate by weight. The felt mixture may include a combination of corrugated paper fibers, fiberglass fibers, and/or wood fibers. The corrugated paper/cardboard fiber component may comprises a range of around seventy to around ninety percent (70%-90%) of the total felt mixture by weight and the fiberglass fiber component may comprise a range of about ten percent to about thirty percent (10%-30%) of the total felt mixture by weight. The felt mixture may include additional components.

Embodiments of the carrier substrate may have a thickness between 17 gauge and 28 gauge as recognized in the art. Other sheet thicknesses are also within the scope of the present invention. For example, felt sheet thicknesses between 10 and 40 gauge are envisioned, but a gauge thickness between 15 gauge and 30 gauge may be preferred. The carrier substrate is a non-woven sheet material made with methods well known in the art. In one embodiment, the substrate is formed by means of a pressurized or open head box, and Fourdrinier or a vat and pick-up felt. The substrate may then be dried by mechanical and vacuum pressing as well as thermal drying. After drying, the substrate may or may not be calendered. The non-woven carrier substrate is then wound and slit for processing and saturation.

The rosin/alum mixture comprises a range of two to ten percent (2-10%) of the total carrier substrate by weight. The rosin/alum mixture may comprise a ratio of alum to rosin (by weight) in a range from about one part alum to one part rosin (1:1) to about four parts alum to about one part rosin (4:1). In one embodiment, the rosin/alum may be added upstream before the non-woven sheet is formed. The combination of the felt mixture and the rosin/alum mixture may result in a carrier substrate that is waterproof or water resistant.

Once the carrier substrate is formed, the continuous non-woven sheet may be submersed in liquid asphalt flux wherein the asphalt flux coats and/or is absorbed into the carrier substrate. Saturating the carrier substrate of the present invention with conventional asphalt can be performed using any process known in the art and with currently existing machinery. One embodiment includes the carrier substrate itself being waterproof or water resistant. As a result, less asphalt may be absorbed into the carrier substrate and the asphalt may coat the outer portion of the carrier substrate. Thus, the asphalt flux that coats and/or saturates the carrier substrate may comprise only around twenty percent to fifty percent (20%-50%) of the total weight of the present roofing underlayment. Therefore, a saturation percentage in a range between about thirty percent and about one-hundred percent (30%-100%) is generally observed, with the preferred saturation being under seventy percent (70%). Currently, a lower saturation percentage when compared to conventional roofing felt is preferred in the commercial embodiment which also maintains or improves the performance characteristics.

FIG. 1 is a summary table of the component make up for one embodiment of the present roofing underlayment corresponding to conventional No. 15 roofing felt. The chart lists the range from lower to upper for each component in this embodiment. As such, the rows list the range of the component, but the columns do not identify the composition of a particular embodiment of the present roofing underlayment. An embodiment corresponding to a conventional No. 15 roofing felt may include the carrier substrate comprising a total weight percentage in a range between around fifty percent to around seventy-five percent (50-75%) of the total weight of the present roofing underlayment. The gauge of the carrier substrate may be between seventeen (17) gauge and twenty-one (21) gauge. The carrier substrate of this embodiment of the present roofing underlayment comprises a combination of a felt mixture and a rosin/alum mixture. The felt mixture comprises ninety to ninety-eight percent (90%-98%) of the total carrier substrate by weight and the rosin/alum mixture comprises around one and one-half percent to around six and two-tenths percent (1.5%-6.2%).

As shown in FIG. 1, the embodiments described include the felt mixture being a combination of corrugated paper and fiberglass fibers, but other components may also be incorporated. The corrugated paper/cardboard component comprises a range of seventy-five to ninety-five percent (75%-95%) of the felt mixture and the fiberglass component comprises a range of five to twenty-five percent (5%-25%) of the felt mixture.

FIG. 2 is a summary table of the component make up for one embodiment of the present roofing underlayment corresponding to conventional No. 30 roofing felt. The chart lists the range from lower to upper for each component in this embodiment. As such, the rows list the range of the individual component, but the columns do not identify the composition of a particular embodiment of the present roofing underlayment. An embodiment corresponding to a conventional No. 30 roofing felt may include the carrier substrate comprising a total weight percentage in a range between around forty-five percent to around seventy-four percent (45-74%) of the total weight of the present roofing underlayment. The gauge of the carrier substrate may be between twenty-four (24) gauge and thirty (30) gauge. The carrier substrate of this embodiment of the present roofing underlayment comprises a combination of a felt mixture and a rosin/alum mixture. The felt mixture comprises ninety to ninety-eight percent (90-98%) of the total carrier substrate by weight and the rosin/alum mixture comprises around two percent to around ten percent (2%-10%).

As shown in FIG. 2, the embodiments described include the felt mixture being a combination of corrugated paper and fiberglass fibers, but other components, such as wood and other fibers may also be incorporated. The corrugated paper/cardboard component comprises a range of seventy-five to ninety-five percent (75%-95%) of the felt mixture and the fiberglass component comprises a range of five to twenty-five percent (5%-25%) of the felt mixture.

Additional individual embodiments of the present roofing underlayment including the components and percentages thereof are presented in FIG. 3. These embodiments include one embodiment have equivalent performance to a conventional No. 15 roofing felt and one embodiment having equivalent performance to a conventional No. 30 roofing felt. As shown in FIG. 3, an embodiment equivalent to a conventional No. 15 roofing felt would utilized a felt having a target thickness of 20 gauge within a margin of +/−1 gauge. In addition, embodiment equivalent to a conventional No. 15 roofing felt would include a target saturation of around forty-four percent (44%). This embodiment of the present roofing underlayment may be equivalent to conventional No. 15 roofing felt and may include a carrier weight of around twenty six (26) pounds per four square roll and an asphalt weight being around eight (8) pounds per four square roll. The carrier substrate may include around ninety-five percent (95%) felt mix and around five percent (5%) chemicals (alum and rosin). The felt may be comprised of around seventy six percent (76%) corrugated fibers, around twelve percent (12%) fiberglass, and around twelve percent (12%) wood fibers. The alum and rosin may have a ratio of around one (1) part rosin to three and two-tenths (3.2) parts alum.

As shown in FIG. 3, an embodiment equivalent to a conventional No. 30 roofing felt would utilize a felt having a target thickness of 26 gauge within a margin of +/−1 gauge. In addition, embodiment equivalent to a conventional No. 30 roofing felt would include a target saturation of around fifty-four percent (54%). One embodiment of the present roofing underlayment equivalent to conventional No. 30 roofing felt may include a carrier weight of around eighteen (18) pounds per two square roll and an asphalt weight being around eleven and seven-tenths (11.7) pounds per two square roll. This embodiment may include a carrier substrate including around ninety-five percent (95%) felt mix and five percent (5%) chemicals (alum and rosin). The felt may be comprised of around eighty eight percent corrugated fibers (88%) and around twelve percent (12%) fiberglass. The alum and rosin may have a ratio of around one (1) part rosin to three and two-tenths (3.2) parts alum. However, an embodiment including the elements in any percentage or ratio that falls within the ranges set forth in FIGS. 1 and 2 are within the scope of the present invention.

In addition, because the carrier substrate may be waterproof or water resistant on its own, it absorbs less asphalt. It was unexpectedly found that the combination of a waterproof or water resistant carrier substrate maintained or exceeded the consumer expected performance when compared to conventional roofing felt even when the carrier substrate of the present roofing underlayment absorbs less asphalt. This allows for the use of less asphalt for the same performance, thereby introducing significant economy into the present roofing underlayment.

As is evident from the foregoing description, certain aspects of the present invention are not limited to the particular details of the examples illustrated herein. It is therefore contemplated that other modifications and applications using other similar or related features or techniques will occur to those skilled in the art. It is accordingly intended that all such modifications, variations, and other uses and applications which do not depart from the spirit and scope of the present invention are deemed to be covered by the present invention.

Other aspects, objects, and advantages of the present invention can be obtained from a study of the drawings, the disclosures, and the appended claims. 

We claim:
 1. A roofing underlayment comprising: a carrier substrate comprising a felt mixture and a binder mixture; a volume of asphalt flux saturating said carrier substrate; wherein said felt mixture comprises between seventy-five percent and ninety-five percent by weight corrugated paper/cardboard fibers and between five percent and twenty-five percent by weight fiberglass fibers; and wherein said binder mixture comprises a mixture of alum and rosin having a mixture ratio by weight of alum to rosin in a range between one to one (1:1) and four to one (4:1).
 2. The roofing underlayment of claim 1 wherein said volume of asphalt flux comprises between twenty-five and fifty percent of a total weight of said roofing shingle underlayment and saturates said carrier substrate at a saturation percentage between thirty and one hundred percent.
 3. The roofing underlayment of claim 2 wherein said volume of asphalt flux saturates said carrier substrate at a saturation percentage between forty and sixty percent.
 4. The roofing underlayment of claim 1 wherein said carrier substrate comprises between fifty and seventy-five percent of a total weight of said roofing underlayment.
 5. The roofing underlayment of claim 4 wherein said volume of asphalt flux saturates said carrier substrate at a saturation percentage between forty and sixty percent.
 6. A roofing underlayment comprising: a carrier substrate comprising a felt mixture and a binder mixture, said felt mixture comprises between seventy-five percent and ninety-five percent by weight corrugated paper/cardboard fibers and between five percent and twenty-five percent by weight fiberglass fibers and said binder mixture comprises a mixture of alum and rosin having a mixture ratio by weight of alum to rosin in a range between one to one (1:1) and four to one (4:1); and a volume of asphalt flux saturating said carrier substrate, wherein said volume of asphalt flux results in a carrier saturation of between forty and fifty-five percent. 